Decapolis = "ten cities"
1) a track of land so called from the ten cities that were in it
1a) according to Pliny, these cities were: Damascus, Opoton, Philadelphia, Raphana, Scythopolis, Gadara, Hippondion, Pella, Galasa, and Canatha (Gill)
Part of Speech: noun proper locative
From G1176 and G4172; the ten city region; the Decapolis, a district in Syria: - Decapolis.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root Δεκάπολις; click on the second column to search for that grammatical form of the root Δεκάπολις; click on the third column to search for that word and grammatical form; click on the total to search for the root Δεκάπολις.